1. Field of the Invention
The present invention relates to: a temperature detector; an image forming device having the temperature detector; and a contamination detection method for the temperature detector.
2. Description of the Related Art
In a fuser of an image forming device, an infrared sensor has conventionally been used to detect a temperature of a fusing roller, but the infrared sensor has been contaminated by paper dust, toner and the like inside the image forming device, which has resulted in an error in temperature detection carried out by the infrared sensor. Therefore, as a solution to this problem, a means for detecting the degree of contamination of an infrared sensor has been proposed. For example, Japanese Unexamined Patent Application Publication No. 2001-34109 discloses a means by which a thermistor that performs temperature compensation on an infrared sensor for detection of a temperature of a fusing roller is provided, thus detecting contamination of the infrared sensor from an output change in the thermistor. Further, Japanese Unexamined Patent Application Publication No. 2006-47411 discloses a means for detecting contamination of an infrared sensor using a heating roller of a fuser by making a comparison between a temperature rise speed of the heating roller, determined in advance and used as the reference, and a temperature rise speed of the heating roller detected by the infrared sensor.
However, in the foregoing means, the degree contamination of an infrared sensor is detected based on the assumption that the infrared sensor is contaminated.